1. Field of the Invention
The present invention relates to an organic solvent-soluble photosensitive polyamide resin. More particularly, the present invention relates to an aromatic polyamide resin having photosensitive radicals and exhibiting satisfactory solubility in certain types of organic solvents and useful for producing a photoset resin product having excellent heat resistance and electrical and mechanical properties.
The organic solvent-soluble photosensitive polyamide resin of the present invention is useful in the semiconductor field as a material for forming insulating films and passivation films for solid-state elements and as an interlaminar insulating material for semiconductor integrated circuits and multilayer printed circuit boards.
2. Description of the Prior Art
In the semiconductor industry, materials for forming insulating films and passivation films for solid-state elements and interlaminar insulating materials for semiconductor integrated circuits and multilayer printed circuit boards must exhibit excellent heat resistance and electrical insulating properties.
Japanese Unexamined Patent Publication (Kokai) Nos. 48-89004, 49-74739 and 56-93704, for example, disclose photosensitive polyamide resins produced by mixing a polyamide resin having no photosensitive radical with a photo-polymerizable unsaturated monomeric compound and, therefore, exhibiting an unsatisfactory photosensitivity.
Japanese Unexamined Patent Publication (Kokai) Nos. 50-8605 and 56-122833 discloses polyamides having photosensitive radicals. These polyamides are aliphatic and, therefore, exhibit unsatisfactory photosensitivity and heat resistance.
There are various approaches for producing passivation films from specific polymer resins having a high insulating property and an excellent heat resistance. Among those various polymers, for example, heat resistant polyimide resins are unsatisfactory in solubility in organic solvents and in photosensitivity. Other polymers, which are soluble in organic solvents and have photosensitive radicals, are produced by amidizing or esterifying carboxyl radicals of a polyamic acid which is a precursor of the corresponding polyimide or polyamideamic acid which is a precursor of the corresponding polyamideimide, and by introducing photosensitive radicals into the amidized or esterified polymer. These photosensitive polymers exhibit a poor stability for storage. Therefore, the precursor polymers having photosensitive radicals must be imidized or amideimidized while or after the precursor polymers are photoset, by means of baking at an elevated temperature. This causes the photoset polyimide or polyamideimide-producing process to be complicated and costly.
In order to cure a photosetting polymer or composition as described above by irradiation, it is necessary to incorporate a photo-polymerization initiator or a sensitizer in an organic solvent solution of this photosetting polymer or composition. Therefore, when the organic solvent is evaporated after coating of the organic solvent solution, such trouble as bleeding of the photo-polymerization initiator or sensitizer is caused.